A non-sterile underlay or overlay through which heated or cooled air is circulated to heat and alternatively cool a patient’s whole-body (i.e., elevate or lower core body temperature) typically in surgical and intensive care settings. Air temperature and flow are regulated by a separate control unit. The device is available in a variety of lengths, widths, thicknesses, and shapes to accommodate body size and application (e.g., adult/paediatric, full-/partial-body). This is a single-use device.